Vacuum skin package having implosion-resistant top web

ABSTRACT

A packaged product has a product surrounded by a vacuum skin package. The vacuum skin package has a support member and an implosion-resistant thermoplastic top web. The top web conforms with both the upper surface of the product, and an uncovered portion of the upper surface of the support member. The thermoplastic top web comprises an ethylene/α-olefin copolymer in an amount of from 55 wt % to 85 wt %, based on total weight of top web, and/or a blend of ethylene/α-olefin copolymer and cyclic olefin copolymer. Also disclosed is a vacuum skin package containing the implosion-resistant top web.

BACKGROUND

Vacuum skin packaging (VSP) is carried out by placing a product on asupport member, placing the support member with product thereon into avacuum chamber in which the atmosphere is evacuated and a top web isdrawn upward against a heated dome and thereafter draped down over thearticle and support member. The top web is made from a thermoplasticmaterial.

After the top web is draped over the released, with the resultingatmospheric pressure forcing the top web to conform to the shape of theproduct and to that portion of the upper surface of the support memberwhich extends around the product and is not covered by the product. As aresult, the top web conforms precisely to the product and thesurrounding portion of the upper surface of the support member, andtogether with the support member, forms a vacuum skin package whichsurrounds the product. When the vacuum is released from the chamber andatmospheric pressure comes to bear on the top web, the top web isthermoformed to take (i) the shape of the exposed extending portion ofthe support member, as well as (ii) the shape of the exposed surface ofthe product.

SUMMARY

Depending upon the nature of the product and the shape of the supportmember, the atmosphere can cause portions of the heated top web to bestretched to a high degree. It has been found that for some products,and with some support members, the top web can be drawn so much that it“implodes,” i.e., fractures in a manner that forms one or more holes inthe top web.

Various food products which can cause the top web to implode include,for example, a plurality of bone-in pork chops in a shingled arrangementon the top of the support member. Another embodiment that can cause topweb implosion is two products placed flat down on the support memberwithout touching one another but with a small gap therebetween. Yetanother embodiment is a plurality of pork chops in overlappingrelationship with an unfilled volume beneath (commonly referred to as an“undercut”) at least a portion of one of the chops, with the top webbeing so drawn into the unfilled volume by the returning atmosphere thatthe top web fractures during the final stage of forming the vacuum skinpackage. In has been found that bone-in meat products produce a greaterimplosion challenge than boneless meat products.

Another factor which can enhance the risk of top web implosion is asupport member in the form of a tray having side walls extending upwardfrom a product support surface. During the formation of the vacuum skinpackage, the top web is drawn more in order to cover the exposedsurfaces of the side walls as well as any exposed surface of the productsupport surface.

A first aspect is directed to a packaged product comprising a productand a vacuum skin package surrounding the product. The vacuum skinpackage comprises a support member having an upper surface, and animplosion-resistant thermoplastic top web. In the package, the top webconforms to both (i) an upper surface of the product, and (ii) a portionof the upper surface of the support member, the portion being uncoveredby the product. The thermoplastic top web comprises a member selectedfrom the group consisting of: (iii) at least one ethylene/α-olefincopolymer in a total amount of from 55 wt % to 85 wt %, based on totalweight of the top web, and (iv) a blend of ethylene/α-olefin copolymerand cyclic olefin copolymer, the ethylene/α-olefin being present in thetop web in a total amount of from 30 wt % to 80 wt %, and the cyclicolefin copolymer being present in the top web in a total amount of fromabout 1 wt % to 50 wt %, based on total weight of the top web.

In an embodiment, the thermoplastic top web comprises a member selectedfrom the group consisting of (iii) at least one ethylene/α-olefincopolymer in a total amount of from 60 wt % to 80 wt %, based on totalweight of the top web, and (iv) a blend of ethylene/α-olefin copolymerand cyclic olefin copolymer, with the ethylene/α-olefin being present inthe top web in a total amount of from 40 wt % to 80 wt %, and with thecyclic olefin copolymer being present in the top web in a total amountof from 1.5 wt % to 35 wt %, based on total weight of the top web.

In an embodiment, the thermoplastic top web comprises a member selectedfrom the group consisting of (iii) at least one ethylene/α-olefincopolymer in a total amount of from 65 wt % to 80 wt %, based on totalweight of the top web, and (iv) a blend of ethylene/α-olefin copolymerand cyclic olefin copolymer, with the ethylene/α-olefin being present inthe top web in a total amount of from 50 wt % to 75 wt %, and with thecyclic olefin copolymer being present in the top web in a total amountof from 2 wt % to 20 wt %, based on total weight of the top web.

In an embodiment, the thermoplastic top web comprises a member selectedfrom the group consisting of (iii) at least one ethylene/α-olefincopolymer in a total amount of from 70 wt % to 80 wt %, based on totalweight of the top web, and (iv) a blend of ethylene/α-olefin copolymerand cyclic olefin copolymer, with the ethylene/α-olefin being present inthe top web in a total amount of from 65 wt % to 79 wt %, and with thecyclic olefin copolymer being present in the top web in a total amountof from 2 wt % to 6 wt %, based on total weight of the top web.

A second aspect is directed to a vacuum skin package having animplosion-resistant top web comprising a member selected from the groupconsisting of (A) at least one ethylene/α-olefin copolymer in a totalamount of from 55 wt % to 85 wt %, based on total weight of the top web,and (B) a blend of ethylene/α-olefin copolymer and cyclic olefincopolymer, the ethylene/α-olefin being present in the top web in a totalamount of from 30 wt % to 80 wt %, and the cyclic olefin copolymer beingpresent in the top web in a total amount of from about 1 wt % to 50 wt%, based on total weight of the top web. The vacuum skin package of thesecond aspect can have any of the packaging article features inaccordance with the first aspect.

A third aspect is directed to a vacuum skin package having animplosion-resistant top web. The implosion resistant top web includes amultilayer film comprising a heat-seal and product-contact layer, aheat-resistant outside layer, an oxygen barrier layer, a first tielayer, a second tie layer, a first bulk layer, and a second bulk layer.The heat seal and product contact layer comprises at least oneethylene/α-olefin copolymer in a total amount of from 40 wt % to 95 wt%, based on weight of the heat seal and product contact layer, and acyclic olefin copolymer in an amount of from 1 wt % to 50 wt %, based onweight of the heat seal and product contact layer. The heat resistantoutside layer comprising at least one member selected from the groupconsisting of low density polyethylene, high density polyethylene,polypropylene, polyester and cyclic olefin copolymer. The oxygen barrierlayer comprises at least one member selected from the group consistingof saponified ethylene/vinyl acetate copolymer, polyvinylidene chloride,and polyamide. The oxygen barrier layer is between the heat-sealproduct-contact layer and the heat resistant outside layer. The firsttie layer comprises at least one member selected from the groupconsisting of ethylene/carboxylic acid copolymer, ethylene/estercopolymer, anhydride-modified ethylene/alpha-olefin copolymer,anhydride-modified high density polyethylene, and anhydride modified lowdensity polyethylene. The first tie layer is between the oxygen barrierlayer and the heat seal and product-contact layer. The second tie layercomprises at least one member selected from the group consisting ofethylene/carboxylic acid copolymer, ethylene/ester copolymer,anhydride-modified ethylene/alpha-olefin copolymer, anhydride-modifiedhigh density polyethylene, and anhydride modified low densitypolyethylene. The second tie layer is between the oxygen barrier layerand the heat resistant outside layer. The first bulk layer comprises atleast one member selected from the group consisting ofethylene/alpha-olefin copolymer, cyclic olefin copolymer, olefinhomopolymer, ethylene/unsaturated ester copolymer, ionomer resin,propylene/ethylene copolymer, polystyrene, polyamide, polyester, andpolycarbonate. The first bulk layer is between the first tie layer andthe heat seal and product-contact layer. The second bulk layer comprisesat least one member selected from the group consisting ofethylene/alpha-olefin copolymer, cyclic olefin copolymer, olefinhomopolymer, ethylene/unsaturated ester copolymer, ionomer resin,propylene/ethylene copolymer, polystyrene, polyimide, polyester, andpolycarbonate. The second bulk layer is between the second tie layer andthe outer abuse layer.

In an embodiment, the heat seal and product contact layer comprises theethylene/α-olefin copolymer in a total amount of from 45 wt % to 90 wt%, based on weight of the heat seal and product contact layer, and thecyclic olefin copolymer is present in an amount of from 5 wt % to 47 wt%, based on weight of the heat seal and product contact layer. Inanother embodiment, the heat seal and product contact layer comprisesthe ethylene/α-olefin copolymer in a total amount of from 50 wt % to 85wt %, based on weight of the heat seal and product contact layer, andthe cyclic olefin copolymer is present in an amount of from 15 wt % to44 wt %, based on weight of the heat seal and product contact layer. Inanother embodiment, the heat seal and product contact layer comprisesthe ethylene/α-olefin copolymer in a total amount of from 55 wt % to 80wt %, based on weight of the heat seal and product contact layer, andthe cyclic olefin copolymer is present in an amount of from 25 wt % to40 wt %, based on weight of the heat seal and product contact layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a cross-sectional view of a multilayer filmsuitable for use as a top web.

FIG. 2 is a schematic of a process for producing a multilayer filmsuitable for use as a top web in a vacuum skin package, i.e., such asthe film of FIG. 1 .

FIG. 3 is a schematic of a test block used in an Implosion ResistanceTest, with film being tested thereon.

FIG. 4 is a perspective view of a vacuum skin package having a pluralityof bone-in pork chops.

DETAILED DESCRIPTION

As used herein, the term “film” is used in a generic sense to includeplastic web, regardless of whether it is film or sheet.

As used herein, the term “packaged product” refers to a product packagedin a packaging article.

As used herein, the term “packaging article” refers to an article madefrom packaging materials, the article surrounding a product or beingdesigned to surround a product.

As used herein, the phrases “seal layer”, “sealing layer”, “heat seallayer”, and “sealant layer”, refer to an outer film layer, or layers,involved in the sealing of the film to itself, another film layer of thesame or another film, and/or another article which is not a film. Thephrase “sealant layer” generally refers to the inside film layer of apackage, the inside layer frequently also serving as a food contactlayer in the packaging of foods.

As used herein, the term “seal” refers to any seal of a first region ofa film surface to a second region of a film surface, wherein the seal isformed by heating the regions to at least their respective sealinitiation temperatures. The heating can be performed by any one or moreof a wide variety of manners, such as using a hot wire, hot knife,heated bar, hot air, infrared radiation, ultrasonic sealing, etc. Morepreferably, the seal is formed by hot wire and/or hot knife. As is knownto those of skill in the art, a static lap seal is another seal usefulin forming a package from the film of the present invention.

As used herein, the term “polymer” refers to the product of apolymerization reaction, and is inclusive of homopolymers, copolymers,terpolymers, etc. In general, the layers of a film can consistessentially of a single polymer, or can have still additional polymerstogether therewith, i.e., blended therewith.

As used herein, the term “copolymer” refers to polymers formed by thepolymerization reaction of at least two different monomers. For example,the term “copolymer” includes the copolymerization reaction product ofethylene and an alpha-olefin, such as 1-hexene. However, the term“copolymer” is also inclusive of, for example, the copolymerization of amixture of ethylene, propylene, 1-hexene, and 1-octene.

As used herein, a copolymer identified in terms of a plurality ofmonomers, e.g., “propylene/ethylene copolymer”, refers to a copolymer inwhich either monomer may copolymerize in a higher weight or molarpercent than the other monomer or monomers. However, the first listedmonomer preferably polymerizes in a higher weight percent than thesecond listed monomer, and, for copolymers which are terpolymers,quadripolymers, etc., preferably the first monomer copolymerizes in ahigher weight percent than the second monomer, and preferably the secondmonomer copolymerizes in a higher weight percent than the third monomer,etc.

As used herein, copolymers are identified, i.e., named, in terms of themonomers from which the copolymers are produced. For example, the phrase“propylene/ethylene copolymer” refers to a copolymer produced by thecopolymerization of both propylene and ethylene, with or withoutadditional comonomer(s).

As used herein, terminology employing a “/” with respect to the chemicalidentity of a copolymer (e.g., “an ethylene/alpha-olefin copolymer”),identifies the comonomers which are copolymerized to produce thecopolymer. As used herein, “ethylene alpha-olefin copolymer” is theequivalent of “ethylene/alpha-olefin copolymer.”

As used herein, the phrase “heterogeneous polymer” refers topolymerization reaction products of relatively wide variation inmolecular weight and relatively wide variation in compositiondistribution, i.e., typical polymers prepared, for example, usingconventional Ziegler-Natta catalysts. Heterogeneous polymers are usefulin various layers of the film used in the present invention. Althoughthere are a few exceptions (such as TAFMER®) linear homogeneousethylene/alpha-olefin copolymers produced by Mitsui PetrochemicalCorporation, using Ziegler-Natta catalysts), heterogeneous polymerstypically contain a relatively wide variety of chain lengths andcomonomer percentages.

As used herein, the phrase “homogeneous polymer” refers topolymerization reaction products of relatively narrow molecular weightdistribution and relatively narrow composition distribution. Homogeneouspolymers are useful in various layers of the multilayer film used in thepresent invention. Homogeneous polymers are structurally different fromheterogeneous polymers, in that homogeneous polymers exhibit arelatively even sequencing of comonomers within a chain, a mirroring ofsequence distribution in all chains, and a similarity of length of allchains, i.e., a narrower molecular weight distribution. Furthermore,homogeneous polymers are typically prepared using metallocene, or othersingle-site type catalysis, rather than using Ziegler Natta catalysts.

More particularly, homogeneous ethylene/alpha-olefin copolymers may becharacterized by one or more methods known to those of skill in the art,such as molecular weight distribution (M_(w)/M_(n)), compositiondistribution breadth index (CDBI), and narrow melting point range andsingle melt point behavior. The molecular weight distribution(M_(w)/M_(n)), also known as polydispersity, may be determined by gelpermeation chromatography. The homogeneous ethylene/alpha-olefincopolymers useful in this invention generally has (M_(w)/M_(n)) of lessthan 2.7; preferably from about 1.9 to 2.5; more preferably, from about1.9 to 2.3. The composition distribution breadth index (CDBI) of suchhomogeneous ethylene/alpha-olefin copolymers will generally be greaterthan about 70 percent. The CDBI is defined as the weight percent of thecopolymer molecules having a comonomer content within 50 percent (i.e.,plus or minus 50%) of the median total molar comonomer content. The CDBIof linear polyethylene, which does not contain a comonomer, is definedto be 100%. The Composition Distribution Breadth Index (CDBI) isdetermined via the technique of Temperature Rising Elution Fractionation(TREF). CDBI determination clearly distinguishes the homogeneouscopolymers used in the present invention (narrow compositiondistribution as assessed by CDBI values generally above 70%) fromheterogeneous polymers such as VLDPE's which are available commerciallywhich generally have a broad composition distribution as assessed byCDBI values generally less than 55%. The CDBI of a copolymer is readilycalculated from data obtained from techniques known in the art, such as,for example, TREF as described, for example, in Wild et. al., J. Poly.Sci. Poly. Phys. Ed., Vol. 20, p.441 (1982). Preferably, the homogeneousethylene/alpha-olefin copolymers have a CDBI greater than about 70%,i.e., a CDBI of from about 70% to 99%. Such homogeneous polymers exhibita relatively narrow melting point range, in comparison with“heterogeneous copolymers”, i.e., polymers having a CDBI of less than55%. Preferably, the homogeneous ethylene/alpha-olefin copolymersexhibit an essentially singular melting point characteristic, with apeak melting point (T_(m)), as determined by Differential ScanningColorimetry (DSC), of from about 60° C. to 105° C. Preferably thehomogeneous copolymer has a DSC peak T_(m) of from about 80° C. to 100°C. As used herein, the phrase “essentially single melting point” meansthat at least about 80%, by weight, of the material corresponds to asingle T_(m) peak at a temperature within the range of from about 60° C.to 105° C., and essentially no substantial fraction of the material hasa peak melting point in excess of about 115° C., as determined by DSCanalysis. DSC measurements are made on a Perkin Elmer System 7 ThermalAnalysis System. Melting information reported are second melting data,i.e., the sample is heated at a programmed rate of 10° C./min. to atemperature below its critical range. The sample is then reheated (2ndmelting) at a programmed rate of 10° C./min. The presence of highermelting peaks is detrimental to film properties such as haze, andcompromises the chances for meaningful reduction in the seal initiationtemperature of the final film.

A homogeneous ethylene/alpha-olefin copolymer can, in general, beprepared by the copolymerization of ethylene and any one or morealpha-olefin. Preferably, the alpha-olefin is a C₃-C₂₀ alpha-monoolefin,more preferably, a C₄-C₁₂ alpha-monoolefin, still more preferably, aC₄-C₈ alpha-monoolefin. Still more preferably, the alpha-olefincomprises at least one member selected from the group consisting ofbutene-1, hexene-1, and octene-1, i.e., 1-butene, 1-hexene, and1-octene, respectively. Most preferably, the alpha-olefin comprisesoctene-1, and/or a blend of hexene-1 and butene-1.

Processes for preparing and using homogeneous polymers are disclosed inU.S. Pat. Nos. 5,206,075, 5,241,031, and PCT International ApplicationWO 93/03093, each of which is hereby incorporated by reference thereto,in its entirety. Further details regarding the production and use ofhomogeneous ethylene/alpha-olefin copolymers are disclosed in PCTInternational Publication Number WO 90/03414, and PCT InternationalPublication Number WO 93/03093, both of which designate Exxon ChemicalPatents, Inc. as the Applicant, and both of which are herebyincorporated by reference thereto, in their respective entireties.

Still another genus of homogeneous ethylene/alpha-olefin copolymers isdisclosed in U.S. Pat. No. 5,272,236, to LAI, et. al., and U.S. Pat. No.5,278,272, to LAI, et. al., both of which are hereby incorporated byreference thereto, in their respective entireties.

As used herein, the term “polyolefin” refers to any polymerized olefin,which can be linear, branched, cyclic, aliphatic, aromatic, substituted,or unsubstituted. More specifically, included in the term polyolefin arehomopolymers of olefin, copolymers of olefin, copolymers of an olefinand a non-olefinic comonomer copolymerizable with the olefin, such asvinyl monomers, modified polymers thereof, and the like. Specificexamples include polyethylene homopolymer, polypropylene homopolymer,polybutene, ethylene/alpha-olefin copolymer, propylene/alpha-olefincopolymer, butene/alpha-olefin copolymer, ethylene/vinyl acetatecopolymer, ethylene/ethyl acrylate copolymer, ethylene/butyl acrylatecopolymer, ethylene/methyl acrylate copolymer, ethylene/acrylic acidcopolymer, ethylene/methacrylic acid copolymer, modified polyolefinresin, ionomer resin, polymethylpentene, etc. Modified polyolefin resinis inclusive of modified polymer prepared by copolymerizing thehomopolymer of the olefin or copolymer thereof with an unsaturatedcarboxylic acid, e.g., maleic acid, fumaric acid or the like, or aderivative thereof such as the anhydride, ester or metal salt or thelike. It could also be obtained by incorporating into the olefinhomopolymer or copolymer, an unsaturated carboxylic acid, e.g., maleicacid, fumaric acid or the like, or a derivative thereof such as theanhydride, ester or metal salt or the like.

As used herein, terms identifying polymers, such as “polyamide”,“polyester”, “polyurethane”, etc. are inclusive of not only polymerscomprising repeating units derived from monomers known to polymerize toform a polymer of the named type, but are also inclusive of comonomers,derivatives, etc. which can copolymerize with monomers known topolymerize to produce the named polymer. For example, the term“polyamide” encompasses both polymers comprising repeating units derivedfrom monomers, such as caprolactam, which polymerize to form apolyamide, as well as copolymers derived from the copolymerization ofcaprolactam with a comonomer which when polymerized alone does notresult in the formation of a polyamide. Furthermore, terms identifyingpolymers are also inclusive of mixtures, blends, etc. of such polymerswith other polymers of a different type. More preferably, however, thepolyolefin is a the polymerization product of one or more unsubstitutedolefins, the polyamide is the polymerization product of one or moreunsubstituted amides, etc.

As used herein, the phrase “ethylene alpha-olefin copolymer”, and“ethylene/alpha-olefin copolymer”, refer to such heterogeneous materialsas linear low density polyethylene (LLDPE), and very low and ultra-lowdensity polyethylene (VLDPE and ULDPE); and homogeneous polymers such asmetallocene-catalyzed EXACT® linear homogeneous ethylene/alpha olefincopolymer resins obtainable from the Exxon Chemical Company, of Baytown,Tex., and TAFMER® linear homogeneous ethylene/alpha-olefin copolymerresins obtainable from the Mitsui Petrochemical Corporation. All thesematerials generally include copolymers of ethylene with one or morecomonomers selected from C₄ to C₁₀ alpha-olefin such as butene-1 (i.e.,1-butene), hexene-1, octene-1, etc. in which the molecules of thecopolymers comprise long chains with relatively few side chain branchesor cross-linked structures. This molecular structure is to be contrastedwith conventional low or medium density polyethylenes which are morehighly branched than their respective counterparts. The heterogeneousethylene/alpha-olefin commonly known as LLDPE has a density usually inthe range of from about 0.91 grams per cubic centimeter to about 0.94grams per cubic centimeter. Other ethylene/alpha-olefin copolymers, suchas the long chain branched homogeneous ethylene/alpha-olefin copolymersavailable from The Dow Chemical Company, known as AFFINITY® resins, arealso included as another type of homogeneous ethylene/alpha-olefincopolymer useful in the present invention.

In general, the ethylene/alpha-olefin copolymer comprises a copolymerresulting from the copolymerization of from about 80 to 99 weightpercent ethylene and from 1 to 20 weight percent alpha-olefin.Preferably, the ethylene/alpha-olefin copolymer comprises a copolymerresulting from the copolymerization of from about 85 to 95 weightpercent ethylene and from 5 to 15 weight percent alpha-olefin.

As used herein, the phrase “cyclic olefin copolymer” is inclusive of allcyclic olefin polymers. Ethylene norbornene copolymer is a preferredcyclic olefin copolymer. In an embodiment, the ethylene/norbornenecopolymer has a density of less than 0.98 g/cm³. In an embodiment, theethylene/norbornene copolymer has a melt index of less than 1.5 dg/min.

As used herein, the phrases “inner layer” and “internal layer” and“intermediate layer” refer to any layer, of a multilayer film, havingboth of its principal surfaces directly adhered to another layer of themultilayer film.

As used herein, the phrase “outer layer” refers to any film layer offilm having less than two of its principal surfaces directly adhered toanother layer of the film. The phrase is inclusive of monolayer andmultilayer films. In multilayer films, there are two outer layers, eachof which has a principal surface adhered to only one other layer of themultilayer film. In monolayer films, there is only one layer, which, ofcourse, is an outer layer in that neither of its two principal surfacesis adhered to another layer of the film.

As used herein, the phrase “inside layer” refers to the outer layer, ofa multilayer film packaging a product, which is closest to the product,relative to the other layers of the multilayer film. “Inside layer” alsois used with reference to the innermost layer (which is also an outerlayer) of a plurality of concentrically arranged layers extruded throughone or more annular dies. The inside layer is also frequently referredto as the “seal layer” or as the “heat seal layer.”

As used herein, the phrase “outside layer” refers to the outer layer, ofa multilayer film packaging a product, which is furthest from theproduct relative to the other layers of the multilayer film. “Outsidelayer” also is used with reference to the outermost layer of a pluralityof concentrically arranged layers extruded through one or more annulardies.

The packaging article can be used for the packaging of a wide variety ofproducts, including both food products and non-food products. However,the film is especially useful as the top web in a vacuum skin packagefor the packaging of meat products, particularly bone-in meat products(pork chops, steaks, etc) and boneless meat products. Typical meatproducts include beef, pork, foul, fish, lamb, etc., and include freshmeat products and processed meat products, such as sausage. Higherimplosion resistance is needed when vacuum skin packaging a plurality ofbone-in pork chops, steaks, etc, in shingled configuration on thesupport member or in randomly placed configuration on the supportmember.

The top web film used in the packaged product can have a maximumthickness of from 3 to 9 mils, or from 3.2 to 8 mils, or from 3.4 milsto 7.5 mils, or from 3.6 mils to 7 mils, or from 3.8 mils to 6.5 mils,or from 4 mils to 6 mils. As used herein, the phrase “maximum thickness”is used because the top web is produced at a desired thickness but someportions of the top web are drawn down (i.e., reduced in thickness) bythe thermoforming which occurs during the process of making a vacuumskin package. The portions of the top web which are not drawn downduring the packaging process retain the maximum thickness of the topweb, i.e., the original thickness of the top web before it is used inthe vacuum skin packaging process.

In an embodiment, the top web film may have following layer arrangement:

(inside) Seal/1^(st) Bulk/1^(st) Tie/O₂-Barrier/2^(nd) Tie/2^(nd)Bulk/Abuse (outside)

In another embodiment, the top web film is made from a multilayer filmof the following layer arrangement:

(inside) Seal/1^(st) Bulk/2^(nd) Bulk/1^(st) Tie/O₂-Barrier/2^(nd)Tie/2^(nd) Bulk/Abuse (outside)

In an embodiment, the top web does not comprise ethylene/vinyl acetatecopolymer.

In an alternative embodiment, the top web comprises ethylene/vinylacetate copolymer in an amount of from 1 wt % to 10 wt %, based on totaltop web weight.

In an embodiment, the top web does not comprise ionomer resin.

In an alternative embodiment, top web comprises ionomer resin in anamount of from 1 wt % to 10 wt %, based on total top web weight.

FIG. 1 illustrates a seven layer film 10 is designed primarily forvacuum packaging and especially for vacuum skin packaging. Film 10 isdesigned for use as the outer top web film for use in a vacuum skinpackage. The core layer 12 is an oxygen barrier layer. Intermediatelayer 18 is a first tie layer. Intermediate layer 20 is a second tielayer. Outer layer 24 is a heat seal and product-contact layer. Outerlayer 22 is an outer abuse layer. Intermediate layer 14 is a first bulklayer, and is between the first tie layer 18 and outer layer 24.Intermediate layer 16 is a second bulk layer, and is between second tielayer 20 and outer abuse layer 22.

In an embodiment of the multilayer top web film, the outer heat seal andproduct-contact layer can comprise at least one member selected from thegroup consisting of ethylene/α-olefin copolymer, cyclic olefincopolymer, low density polyethylene, high density polyethylene,ethylene/vinyl acetate copolymer with a vinyl acetate content in the 3%to 9% range by weight, ionomer resin, ethylene methacrylic acidcopolymer, and ethylene methyl acrylate copolymer. In anotherembodiment, the outer heat seal layer comprises ethylene/α-olefincopolymer and cyclic olefin copolymer. In another embodiment, the outerheat seal and product contact layer comprises ethylene/α-olefincopolymer and cyclic olefin copolymer and at least one member selectedfrom the group consisting of low density polyethylene, high densitypolyethylene, ethylene/vinyl acetate copolymer with a vinyl acetatecontent in the 3% to 9% range by weight, ionomer resin, ethylenemethacrylic acid copolymer, and ethylene methyl acrylate copolymer.

In an embodiment, the top web has a seal layer comprising from 10 wt %to 50 wt % cyclic olefin copolymer in a blend with from 40 wt % to 90 wt% ethylene/α-olefin copolymer. In another embodiment, the top web has aseal layer comprising from 15 wt % to 45 wt % cyclic olefin copolymer ina blend with from 45 wt % to 85 wt % ethylene/α-olefin copolymer. Inanother embodiment, the top web has a seal layer comprising from 20 wt %to 40 wt % cyclic olefin copolymer in a blend with from 50 wt % to 80 wt% ethylene/α-olefin copolymer. In another embodiment, the top web has aseal layer comprising from 25 wt % to 40 wt % cyclic olefin copolymer ina blend with from 55 wt % to 70 wt % ethylene/α-olefin copolymer.

The outer heat seal and product-contact layer of the top web can containone or more olefin homopolymer or ethylene/α-olefin copolymer whichtogether have an average density of less than 0.92 g/cc, or less than0.915 g/cc, or less than 0.912 g/cc, or less than 0.910 g/cc, or lessthan 0.909 g/cc, or less than 0.908 g/cc, or less than 0.907 glee, orless than 0.906 g/cc, or less than 0.905 g/cc, or less than 0.904 g/cc,or less than 0.903 g/cc, or from 0.900 to 0.915 g/cc, or from 0.900 to0.92 g/cc or from 0.900 to 0.910 g/cc, or from 0.901 to 0.909 g/cc, orfrom 0.902 to 0.908 g/cc, or from 0.903 to 0,907 g/cc.

The heat seal layer can have a thickness of at least 0.1 mil, or from0.15 to 5 mils, or from 0.18 to 4 mils, or from 0.2 to 2 mils, or from0.1 to 1.5 mil, or from 0.2 to 1.1 mil, or from 0.25 to 1 mil; or from0.3 to 0.8 mil, or from 0.35 to 0.7 mil, or from 0.35 to 0.6 mil, orfrom 0.4 to 0.6 mil, or from 0.4 to 0.6 mil, or about 0.5 mil.

The top web can comprise a first bulk layer between the first tie layerand the heat seal and product-contact layer, and a second bulk layerbetween the second tie layer and the outer abuse layer.

In an embodiment, each of the bulk layers comprises at least one memberselected from the group consisting of ethylene/alpha-olefin copolymerand cyclic olefin copolymer.

In another embodiment, each of the bulk layers comprises at least onemember selected from the group consisting of ethylene/alpha-olefincopolymer, cyclic olefin copolymer, ethylene homopolymer,ethylene/unsaturated ester copolymer, ionomer resin, propylene/ethylenecopolymer, polystyrene, polyamide, polyester, and polycarbonate. Bulklayers are usually relatively thick, and/or are made from relativelystrong polymers, as the purpose of bulk layers is to add strength,puncture resistance, etc. to the film.

If a blend of more than one ethylene/α-olefin copolymer is present, theblend is herein characterized as having an “average density” which isthe weighted average of the densities of the various ethylene/α-olefincopolymers present, i.e., the densities of the various ethylene/α-olefincopolymers present taken in combination with their relative weightpercent's in the blend. Similarly, the density of differentethylene/α-olefin copolymers in the heat seal and product-contact layer,together with the ethylene/α-olefin copolymers in the intermediate hulklayers, or any subset or set of layers, including up to all of thelayers of the film, can be expressed as an “average density,”characterized with a weighted average of the densities of the group ofpolymers even if they are present in different layers, i.e., not allblended together.

The ethylene/α-olefin copolymers are primarily present in the heat-sealand product-contact layer and in the bulk layers. In an embodiment, theethylene/α-olefin copolymer(s) in the top web have an average density offrom 0.88 g/cm³ to 0.915 g/cm³. In another embodiment, theethylene/α-olefin copolymer(s) in the top web have an average density offrom 0.885 g/cm³ to 0.91 g/cm³. In another embodiment, theethylene/α-olefin copolymer(s) in the top web have an average density offrom 0.885 g/cm³ to 0.91 g/cm³. In another embodiment, theethylene/α-olefin copolymer in the top web has a density of from 0.90g/cm³ to 0.91 g/cm³. In another embodiment, the ethylene/α-olefincopolymer(s) in the top web have an average density of from 0.902 g/cm³to 0.908 g/cm³. In another embodiment, the ethylene/α-olefincopolymer(s) in the top web have an average density of from 0.90 g/cm³to 0.91 g/cm³.

In another embodiment, the ethylene/α-olefin copolymer comprises atleast one heterogeneous ethylene/α-olefin copolymer(s) having an averagedensity of from 0.90 g/cm³ to 0.91 g/cm³. In another embodiment, theethylene/α-olefin copolymer comprises at least one heterogeneousethylene/α-olefin copolymer(s) having an average density of from 0.902g/cm³ to 0.908 g/cm³. In another embodiment, the ethylene/α-olefincopolymer comprises at least one heterogeneous ethylene/α-olefincopolymer(s) having an average density of from 0.904 g/cm³ to 0.906g/cm³.

In an embodiment, the top web film comprises ethylene/α-olefin copolymerhaving a melt index of from 0.5 to 4 dg/min, or 0.8 to 3 dg/min, or from1 to 2 dg/min. In an embodiment, the top web film comprisesethylene/α-olefin copolymers having an average melt index of from 0.5 to4 dg/min, or 0.8 to 3 dg/min, or from 1 to 2 dg/min. The average meltindex is a weighted average of all the ethylene/alpha-olefin copolymerin the top web, determined in a manner corresponding with the manner inwhich average density is determined, as described herein. That is, theaverage density of more than one ethylene/alpha-olefin copolymer is aweighted average.

The multilayer top web film can comprise an oxygen barrier layercomprising a member selected from the group consisting of saponifiedethylene/vinyl acetate copolymer, polyvinylidene chloride, andpolyamide.

The multilayer top web film can comprise an outer abuse layer designedfor the exterior of the final package. The abuse layer provides heatresistance during the vacuum skin packaging process.

The abuse layer may comprise at least one member selected from the groupconsisting of low density polyethylene, high density polyethylene,polypropylene, polyester (particularly polyethylene terephthalate), andcyclic olefin copolymer. For processability, melt indices of betweenabout 5 and 8 are preferred for the abuse layer.

The top web can comprise a first tie layer between the oxygen barrierlayer and the heat seal and product-contact layer, and a second tielayer between the oxygen barrier layer and the outer abuse layer.Preferred polymers for use in tie layers include ethylene/carboxylicacid copolymer, ethylene/ester copolymer, and anhydride-modifiedethylene/alpha-olefin copolymer, anhydride-modified high densitypolyethylene, and anhydride modified low density polyethylene.Generally, tie layers are relatively thin, as their purpose is simply toprovide a chemically compatible composition between two layers whichotherwise do not bond with one another to a desired degree.

The film from which the top web is made may be partially or whollyirradiated to induce crosslinking. In the irradiation process, the filmis subjected to an energetic radiation treatment, such as coronadischarge, plasma, flame, ultraviolet, X-ray, gamma ray, beta ray, andhigh energy electron treatment, which induce cross-linking betweenmolecules of the irradiated material. The irradiation of polymeric filmsis disclosed in U.S. Pat. No. 4,064,296, to BORNSTEIN, et. al., which ishereby incorporated in its entirety, by reference thereto. BORNSTEIN,et. al. discloses the use of ionizing radiation for crosslinking thepolymer present in the film. The extrusion coating process illustratedin FIG. 2 (described below) allows various layers to be extruded andcrosslinked before an irradiation-sensitive polyvinylidene chlorideO₂-barrier layer and other layers are extruded on top of the irradiated,crosslinked substrate portion of the multilayer film tubing, resultingin a stronger tubing film, whereas a full coextrusion of all the layerstogether, followed by irradiation, could result in degradation of thePVDC layer, causing a decrease in its oxygen barrier properties.

To produce crosslinking, a suitable radiation dosage of high energyelectrons, preferably using an electron accelerator, with a dosage levelbeing determined by standard dosimetry methods. Other accelerators suchas a Van de Graaf generator or resonating transformer may be used. Theradiation is not limited to electrons from an accelerator since anyionizing radiation may be used. The ionizing radiation can be used tocrosslink the polymers in the film.

Although not illustrated in FIG. 2 , preferably the film is irradiatedat a level of from 180-220 kGy (kilograys). As can be seen from thedescriptions of preferred films for use in the present invention, themost preferred amount of radiation is dependent upon the filmcomposition, thickness, etc., and its end use.

In an embodiment, the support member is a multilayer structurecomprising a support sheet having a liner film laminated thereto. In anembodiment, the support sheet is made from a member selected from thegroup consisting of polypropylene and polyethylene terephthalate.

In an embodiment, the liner film is a multilayer film having a bondinglayer which is adhered to the support sheet, an outer heat seal &food-contact layer, and an oxygen barrier layer between the heat seal &food-contact layer and the bonding layer. The oxygen barrier layer maycomprise a member selected from the group consisting of saponifiedethylene/vinyl acetate copolymer, polyvinylidene chloride, andpolyamide.

In the liner film, the heat seal & food-contact layer may comprise anyof the above-described polymers to be used in the heat seal andproduct-contact layer of the multilayer top web film.

In the liner film, the bonding layer may comprise anhydride graftedpolypropylene.

In the liner film, the tie layer, which is between the oxygen barrierlayer and the heat seal & food-contact layer, may comprise at least onemember selected from the group consisting of ethylene/carboxylic acidcopolymer, ethylene/ester copolymer, anhydride-modifiedethylene/alpha-olefin copolymer, anhydride-modified high densitypolyethylene, and anhydride modified low density polyethylene. This tielayer may be a first tie layer comprising an anhydride modifiedethylene/α-olefin copolymer, with the liner film further comprising asecond tie layer which is between the first tie layer and the heat seal& food-contact layer. The second tie layer may comprise ethylene/methylacrylate copolymer.

The liner film may have a maximum thickness of from 1.2 mils to 2 mils,or 1.4 mils to 1.8 mils.

In an embodiment, the support member is flat and comprises a flatsupport sheet and a flat liner film.

In an embodiment, the support member is a tray having a bottom productsupport portion and side walls extending upwardly from the productsupport portion, with the tray comprising a laminate comprising asupport member having a liner film bonded thereto. An unformed laminatecan be thermoformed to form the tray.

Various films were produced in the form of multilayer film tubings,using the process illustrated in FIG. 2 . The process of FIG. 2 is asgenerally disclosed in U.S. Pat. No. 4,287,151, to ESAKOV, et. al.,hereby incorporated by reference thereto, in its entirety.

In the process illustrated in FIG. 2 , tubular extrudate 260 wasdownwardly formed from die 262, the tubular extrudate enclosing airmandrel 264. At approximately this point in the process, an exteriorcooling means, in the form of water ring 266, encircles tubularextrudate 260. Water ring 266 in the shape of a circular tray, had anopening therethrough, the opening having a diameter slightly larger thanthat of tubular extrudate 260. A constant flow of water, at about 50°F., is supplied to water ring 266. The overflow from the water ringprovided an annular film of water on the outer surface of extrudate 260.The water fell downwardly around the entire outer periphery of extrudate260, thereby cooling extrudate 260. The film of water is collected byreceptacle 268. Water was the preferred cooling medium because its heatcapacity and heat transfer characteristics are such as to cool extrudate260 more rapidly than a chilled gas would have. However, as analternative to water ring 266, a fine spray of cooled water could havebeen directed against the exterior surface of the extrudate 260. Incombination, air mandrel 264 and water ring 266 serve as the means tocool and solidify extrudate 260. In some instances, depending upon thepolymer being extruded and upon the wall thickness of extrudate 260,either the interior or exterior cooling could be eliminated, because onecooling means alone would be sufficient to solidify the interior tubewall before reaching support plug 270. Once solidified, extrudate 272 iscollapsed by rolls 274, to form a solidified lay flat tubing 276. Thewound up film can be irradiated before windup or unwound and irradiatedbefore use.

FIG. 4 illustrates packaged product 80 comprising a plurality of porkchops 82 having bones 84 are more or less randomly arranged on athermoformed tray 86 which is a support member made from a polypropylenesheet to which a liner film has been bonded, with the resulting laminatebeing thermoformed into tray 86. The transparent top web has been heatedand draped over tray 86 and product 82, so that product 82 is vacuumpackaged and surrounded by the combination of the transparent top weband the liner film bonded to the support member. As both the liner filmand the top web are multilayer films comprising an oxygen barrier layer,the shelf life of product 82 is extended by vacuum skin package article.The convoluted top surface produced by the random arrangement of thebone-in pork chops 82 produces a plurality of cavities 88 into which thetop web is thermoformed during the vacuum skin packaging process. Unlessthe top web is capable of withstanding the stress of the heavy degree ofthermoforming into cavities 88, the top web will break, causing thepackage to fail. However, the top web utilized in the package of FIG. 4exhibited a high degree of Implosion Resistance, as it is in accord withthe first aspect, described above.

Implosion Resistance Test

The Implosion Resistance Test is illustrated in FIG. 3 . The ImplosionResistance Test measures the maximum diameter of the openings over whichthe top web can be heated and stretched, without breaking, during vacuumskin packaging.

A drilled wooden block 30 is drilled part way through with a series ofbits of different diameters, ranging from the smallest diameter of 5/16(8 mm) inch, to the largest diameter of 1 inch (25.4 mm). In block 30 asillustrated in FIG. 3 , bores 32, 34, 36, 38, and 42 extend into theblock from respective openings. Each bore has been drilled to the samedepth of one inch. The openings are circular holes defined by theintersection of each cylindrical bore with the planar upper face ofwooden block 30.

The block is vacuum skin packaged in a CRYOVAC RTM VS-44 machine. Thetop web film 44 is used to completely envelop the block 80. During thepackaging tests with wooden block 30, the film tends to undergo astretching stress which increases with the increasing hole diameter. Inthe example illustrated in FIG. 3 , film portions 46, 48, 50, 52, and 54stretch without breaking over the holes 32, 34, 36, 38, and 40, but filmportion 56 breaks inside hole 42. The diameter in mm of the largest holebefore the film becomes broken (i.e., hole 40 in the test illustrated inFIG. 2 ) is the implosion resistance rating of the top web film beingtested. The implosion resistance rating is highly representative of thefilm packaging ability of the top web film in a vacuum skin packagingprocess. A set of 44 tests are performed on each film, with the resultsaveraged, to provide an “average implosion resistance”. The test isconducted in a room at 23 C and 1 atm pressure and 50% relativehumidity.

The packaging tests on block 30 were conducted throughout the examplesherein on a CRYOVAC VS44 machine equipped with a rotary vacuum pump anda serially connected auxiliary pump. The temperature under the heaterbell was of 200° C., and the films were infrared pre-heated up to 70° C.to 80° C. The level of the vacuum provided varied between 3 and 6millibars.

The top web film can have an average implosion resistance of at least11.5 millimeters, or at least 13 millimeters, or at least 14millimeters, or at least 14.5 millimeters, or at least 15 millimeters,or at least 15.4 millimeters, or at least 15.8 millimeters, or at least16 millimeters.

Examples

Table 1, below, provides the identity of various resins used in makingvarious working and comparative top web films for the vacuum skinpackage, as well as for a liner film to be adhered to a support sheet tomake the support member on which a product to be packaged is place.

TABLE 1 Generic Resin Name Density Melt Index Resin code Tradename{additional information} (g/cc) (dg/min) Supplier ssPE 1 AFFINITY ®homogeneous ethylene/ 0.870 0.99 Dow EG 8100 G1 octene copolymer ssPE 2AFFINITY ® Homogeneous ethylene/ 0.900 6.0 Dow PL 1281G1 octenecopolymer ssPE 3 EXACT ® Homogeneous ethylene/ 0.900 1.3 ExxonMobil 3128butene copolymer ssPE 4 AFFINITY ® Homogeneous ethylene/ 0.902 3.0 DowPL 1850G octene copolymer ssPE 5 EXCEED ® Homogeneous ethylene/ 0.9121.0 ExxonMobil 1012HA hexene copolymer ssPE 6 EXCEED ® Homogeneousethylene/ 0.912 1.0 ExxonMobil 1012CA hexene copolymer ssPE 7 EXCEED ®Homogeneous ethylene/ 0.912 1.0 ExxonMobil 1012HJ hexene copolymer ssPE8 EXCEED ® Homogeneous ethylene/ 0.918 4.5 ExxonMobil 4518PA hexenecopolymer EtCop INFUSE ® PE Olefin block 0.866 0.5 DOW D9007.10 OBCcopolymer hPE 1 ATTANE ® Ethylene/hexene 0.9052 8.6 Dow 4203 copolymerhPE 2 CV77525 Very low density 0.906 0.45 Westlake polyethylene ChemicalhPE 3 ATTANE ® Heterogeneous 0.912 1.0 Dow 4201G ethylene/octenecopolymer hPE 4 XUS Very low density 0.903 0.5 Dow 61520.15Lpolyethylene HDPE1 SURPASS ® High density 0.968 6.0 Nova HPs667-ABpolyethylene Chemicals. HDPE2 T60-500-119 High density 0.968 6.0 Novapolyethylene Chemicals. LDPE LD259 Low density 0.915 12 ExxonMobilpolyethylene PEC R01C-00 Heterogeneous 0.900 2.0 Ineospropylene/ethylene copolymer ENB 1 8007F-400 Ethylene/norbornene 1.022.04 Topas copolymer Advanced Polymers Inc. ENB 2 TOPAS ®Ethylene/norbornene 0.974 1.0 Topas 9903D-10 copolymer Advanced PolymersInc. EVA1 ELVAX ® Ethylene/vinyl acetate 0.940 0.70 DuPont 3165copolymer (20% VA) EVA2 LEVAMELT Ethylene/vinyl acetate 0.98 3 Lanxess400 copolymer (>20% VA) mEVA BYNEL ® 3861 Anhydride-modified 0.980 2.0DuPont ethylene/vinyl acetate copolymer mLLD 1 BYNEL ® 4125 Maleicanhydride 0.930 2.50 DuPont modified LLDPE mLLD 2 GT4408 Maleicanhydride 0.919 2.30 Westlake modified LLDPE Chemical mLLD3 ADMER Maleicanhydride 0.91 3.1 Mitsui NF518E modified LLDPE Chemical mPP ADMER QBMaleic anhydride 0.9 1.8 Mitsui 520E modified Chemical polypropylene EMASP2205 Ethylene/methyl 0.941 2.0 Westlake acrylate copolymer ChemicalEMAA NUCREL 1202 Ethylene/methacrylic 0.94 1.5 DuPont acid copolymer IONSURLYN ® Ionomer resin 0.940 1.3 DuPont 1601 SBS 1 HYBRAR ®Styrene/butadiene/styrene — 0.5 Kuraray EU 7311 block copolymer SBS 2HYBRAR ® Styrene/butadiene/styrene 0.90 0.7 Kuraray EU 7125 blockcopolymer SBS 3 STYROFLEX ® styrene/butadiene/styrene 1.992 11.0 BASF2G66 block copolymer EVOH E171B ethylene/vinyl alcohol 1.14 1.7Evalca/Kuraray copolymer EVOH2 SOARNOL Hydrolyzed ethylene 1.14 3.5Nippon AT4403 vinyl acetate Gohsei copolymer PA6/66 ULTRAMID ®Polyamide - 6/66 1.13 — BASF C33 LN 01 PAMXD6 MX7007 Polyamide MXD6Mitsubishi AB 10,075ACP Silica in polyethylene 0.97 3.0 Teknor ColorSyloid Concentrate SLIP 1 102109 N,N′-ethylene-bis- 0.93 3.1 Ampacetoleamide in LLDPE SLIP 2 MB50-802 20-40 wt % silica 1.03 8.0 Dow Corning50 wt % UHMW Polysiloxane in 10-30 wt % LDPE SLIP 3 10850 Antiblock andslip in 1.00 2.0 Ampacet polyethylene SLIP4 CONSTAB AB Silica in linearlow 1.03 3.3 IMCD Italia 06051 LD density polyethylene spa

Film No. 1 (Prior Art)

Table A, below, provides the structure and composition of Film No. 1,including the identities of the polymers used in the various layers, thearrangement of the layers, and the thickness of the layers. Film No. 1was a prior art film produced in accordance with the process illustratedin FIG. 2 , described above.

TABLE A Layer Prior Art Top Web Film Layer Seal 1^(st) Bulk 1^(st) TieBarrier 2^(nd) Tie 2^(nd) Bulk Abuse function Layer 95% ssPE8 EVA 1 mLLD1 EVOH mLLD 1 EVA 1 95% HDPE2 ComPosition 5% AB 5% AB wt. % 7.8 31.37.85 8.7 7.85 30.0 6.5 Thickness 0.47 mil 1.88 mil 0.47 mil 0.52 mil0.47 mil 1.80 mil 0.39 mil

Tables 2 through 34, below, provide the structure and composition ofFilm No. 1 through Film No. 32, including the identities of the polymersused in the various layers, the arrangement of the layers, and thethickness of the layers. Films No. 1 through Film No. 34 were allproduced in accordance with the process illustrated in FIG. 2 ,described above.

TABLE 2 Layer Film No. 1 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse function Layer 45% ssPE 2 EVA 1 mLLD 1 EVOHmLLD 1 EVA 1 95% ComPosition 50% ssPE 4 HDPE1 5% SLIP 1 4% SLIP 3 1%SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 3 Layer Film No. 2 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse function Layer 45% ssPE 2 EVA 1 mLLD 2 EVOHmLLD 2 EVA 1 95% ComPosition 50% ssPE 4 HDPE1 5% SLIP 1 4% SLIP 3 1%SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 4 Layer Film No. 3 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse function Layer 45% ssPE 2 ssPE 3 mLLD 2EVOH mLLD 2 ssPE 3 95% ComPosition 50% ssPE 4 HDPE1 5% SLIP 1 4% SLIP 31% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 5 Layer Layer Film No. 4 function Seal 1^(st) Bulk 1^(st) TieBarrier 2^(nd) Tie 2^(nd) Bulk Abuse Layer 35% ssPE 2 ssPE 3 mLLD 2 EVOHmLLD 2 ssPE 3 95% HDPE1 Com- 35% ssPE 4 4% SLIP 3 Position  5% SLIP 1 1%SLIP 2 25% ENB 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 6 Layer Layer Film No. 5 function Seal 1^(st) Bulk 1^(st) TieBarrier 2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 50% ssPE 3 mLLD 2EVOH mLLD 2 50% ssPE 3 95% Com- 50% ssPE 4 50% ssPE 1 50% ssPE 1 HDPE1Position  5% SLIP 1 4% SLIP 3 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.36.7 Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 7 Layer Layer Film No. 6 function Seal 1^(st) Bulk 1^(st) TieBarrier 2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 hPE 1 mLLD 1 EVOHmLLD 1 hPE 1 95% HDPE1 Com- 50% ssPE 4 4% SLIP 3 Position  5% SLIP 1 1%SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 8 Layer Layer Film No. 7 function Seal 1^(st) Bulk 1^(st) TieBarrier 2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 ION mLLD 2 EVOHmLLD 2 ION 95% HDPE1 Com- 50% ssPE 4 4% SLIP 3 Position  5% SLIP 1 1%SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 9 Layer Film No. 8 function Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 70% PEC mLLD 2 EVOH mLLD 270% PEC 95% Com- 50% ssPE 4 30% SBS 1 30% SBS 1 HDPE1 Position  5% SLIP1 4% SLIP 3 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 10 Layer Film No. 9 function Seal 1^(st) Bulk 3^(rd) Bulk 1^(st)Tie Barrier 2^(nd) Tie 4^(th) Bulk 2^(nd) Bulk Abuse Layer 45% ssPE 270% PEC hPE 1 mLLD 2 EVOH mLLD 2 hPE 1 70% PEC 95% HDPE1 Com- 50% ssPE 430% SBS 1 30% SBS 1 4% SLIP 3 Position  5% SLIP 1 1% SLIP 2 wt. % 9.115.2 12.1 3.0 21.2 3.0 12.1 6.1 18.2 Thickness 3 5 4 1 7 1 4 2 6

TABLE 11 Layer Film No. 10 function Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 70% PEC mLLD 2 EVOH mLLD 270% PEC 95% Com- 50% ssPE 4 30% SBS 2 30% SBS 2 HDPE1 Position  5% SLIP1 4% SLIP 3 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 12 Layer Film No. 11 function Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 SBS 3 mLLD 2 EVOH mLLD 2SBS 3 95% HDPE1 Com- 50% ssPE 4 4% SLIP 3 Position  5% SLIP 1 1% SLIP 2wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3 mil0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 13 Layer Film No. 12 function Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 EtCop mLLD 2 EVOH mLLD 2EtCop 95% HDPE1 Com- 50% ssPE 4 4% SLIP 3 Position  5% SLIP 1 1% SLIP 2wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3 mil0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 14 Layer Film No. 13 function Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 50% mLLD 2 80% EVOH mLLD 250% 95% Com- 50% ssPE 4 ssPE 3 20% ssPE 3 HDPE1 Position  5% SLIP 1 50%PAMXD6 50% 4% SLIP 3 ssPE 1 ssPE 1 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.033.3 6.7 Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4mil

TABLE 15 Layer Film No. 14 function Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 50% mLLD 2 80% EVOH mLLD 250% 95% Com- 50% ssPE 4 ssPE 3 20% PA6/66 ssPE 3 HDPE1 Position  5% SLIP1 50% 50% 4% SLIP 3 ssPE 1 ssPE 1 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.033.3 6.7 Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4mil

TABLE 16 Layer Film No. 15 function Seal 1^(st) Bulk 3^(rd) Bulk 1^(st)Tie Barrier 2^(nd) Tie 4^(th) Bulk 2^(nd) Bulk Abuse Layer 45% ssPE 250% ssPE3 mLLD 2 PA6/66 80% PA6/66 mLLD 2 50% ssPE3 95% HDPE1 Corn- 50%ssPE 4 50% ssPE1 EVOH 50% ssPE1 4% SLIP 3 Position  5% SLIP 1 20% 1%SLIP 2 PA6/66 wt. % 8.3 26.7 5 6.7 8.3 6.7 5 26.7 6.7 Thickness 0.5 1.60.3 0.4 0.5 0.4 0.3 1.6 0.4

TABLE 17 Layer Film No. 16 function Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 EVA2 mEVA EVOH mEVA EVA295% HDPE1 Com- 50% ssPE 4 4% SLIP 3 Position  5% SLIP 1 1% SLIP 2 wt. %8.3 30 8.3 8.3 8.3 30 6.7 Thickness 0.5 mil 1.8 mil 0.5 mil 0.5 mil 0.5mil 1.8 mil 0.4 mil

TABLE 18 Layer Film No. 17 function Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse Layer 45% ssPE 2 hPE 1 mLLD 2 80% EVOH mLLD2 hPE 1 95% Com- 50% ssPE 4 20% PA6/66 HDPE1 Position  5% SLIP 1 4% SLIP3 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 19 Layer Film No. 18 function Seal 1^(st) Bulk 1^(st) Tie Barrier2^(nd) Tie 2^(nd) Bulk Abuse Layer 35% ssPE 2 hPE 1 mLLD 2 EVOH mLLD 2hPE 1 95% HDPE1 Com- 35% ssPE 4 4% SLIP 3 Position  5% SLIP 1 1% SLIP 225% ENB2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 20 Film No. 19 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 25% ssPE 2 hPE 1 mLLD 2 EVOH mLLD 2hPE 1 95% ComPosition 30% ssPE 4 HDPE1 5% SLIP 1 4% SLIP 3 40% ENB2 1%SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 21 Film No. 20 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 35% ssPE 2 75% mLLD 2 EVOH mLLD 275% 95% ComPosition 35% ssPE 4 hPE 1 hPE 1 HDPE1 5% SLIP 1 25% 25% 4%SLIP 3 25% ENB2 ENB2 ENB2 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 22 Film No. 21 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 35% ssPE 2 60% mLLD 2 EVOH mLLD 260% 95% ComPosition 35% ssPE 4 hPE 1 hPE 1 HDPE1 5% SLIP 1 40% 40% 4%SLIP 3 25% ENB2 ENB2 ENB2 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 23 Film No. 22 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 35% ssPE 2 40% mLLD 2 EVOH mLLD 240% 95% HDPE1 ComPosition 35% ssPE 4 hPE 1 hPE 1 4% SLIP 3 5% SLIP 1 60%60% 1% SLIP 2 25% ENB2 ENB2 ENB2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 24 Film No. 23 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 35% ssPE 2 40% mLLD 2 EVOH mLLD 240% 95% ComPosition 35% ssPE 4 hPE 1 hPE 1 HDPE1 5% SLIP 1 60% 60% 4%SLIP 3 25% ENB2 ENB1 ENB1 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 25 Film No. 24 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 35% ssPE 2 60% mLLD 2 EVOH mLLD 260% 95% HDPE1 ComPosition 35% ssPE 4 hPE 1 hPE 1 4% SLIP 3 5% SLIP 1 40%40% 1% SLIP 2 25% ENB2 ENB1 ENB1 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 26 Film No. 25 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 35% ssPE 2 75% mLLD 2 EVOH mLLD 275% 95% HDPE1 ComPosition 35% ssPE 4 hPE 1 hPE 1 4% SLIP 3 5% SLIP 1 25%25% 1% SLIP 2 25% ENB2 ENB1 ENB1 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 27 Film No. 26 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 35% ssPE 2 hPE 1 mLLD 2 EVOH mLLD 2hPE 1 95% HDPE1 ComPosition 35% ssPE 4 4% SLIP 3 5% SLIP 1 1% SLIP 2 25%ENB2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 28 Film No. 27 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 25% ssPE 2 hPE 1 mLLD 2 EVOH mLLD 2hPE 1 95% HDPE1 ComPosition 30% ssPE 4 4% SLIP 3 5% SLIP 1 1% SLIP 2 40%ENB2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 29 Film No. 28 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 45% ssPE 2 hPE 2 mLLD 2 EVOH mLLD 2hPE 2 95% HDPE1 ComPosition 50% ssPE 4 4% SLIP 3 5% SLIP 1 1% SLIP 2 wt.% 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3 mil 0.5mil 0.3 mil 2.0 mil 0.4 mil

TABLE 30 Film No. 29 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 45% ssPE 2 hPE 3 mLLD 2 EVOH mLLD 2hPE 3 95% ComPosition 50% ssPE 4 HDPE1 5% SLIP 1 4% SLIP 3 1% SLIP 2 wt.% 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3 mil 0.5mil 0.3 mil 2.0 mil 0.4 mil

TABLE 31 Film No. 30 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 45% ssPE 2 ssPE 5 mLLD 2 EVOH mLLD2 ssPE 5 95% HDPE1 ComPosition 50% ssPE 4 4% SLIP 3 5% SLIP 1 1% SLIP 2wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3 mil0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 32 Film No. 31 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 45% ssPE 2 50% mLLD 2 EVOH mLLD 250% 95% ComPosition 50% ssPE 4 hPE 1 hPE 1 HDPE1 5% SLIP 1 50% 50% 4%SLIP 3 hPE 3 hPE 3 1% SLIP 2 wt. % 8.3 33.3 5.0 8.3 5.0 33.3 6.7Thickness 0.5 mil 2.0 mil 0.3 mil 0.5 mil 0.3 mil 2.0 mil 0.4 mil

TABLE 33 Film No. 32 Layer Seal 1^(st) Bulk 1^(st) Tie Barrier 2^(nd)Tie 2^(nd) Bulk Abuse function Layer 70% ssPE 8 hPE 1 mLLD 1 EVOH mLLD 1hPE 1 95% ComPosition 25% ENB 2 HDPE1 5% SLIP 1 4% SLIP 3 1% SLIP 2 wt.% 8.3 33.3 5.0 8.3 5.0 33.3 6.7 Thickness 0.5 mil 2.0 mil 0.3 mil 0.5mil 0.3 mil 2.0 mil 0.4 mil

TABLE 34 Tray Liner Film Layer function Seal (food Bonding (adhered tocontact layer) Tie Tie Barrier polypropylene sheet) Layer Composition50% LDPE 49% EMAA 1% SLIP1 EMA mLLD 3 EVOH2 mPP wt. % 4.7 14.0 20.9 14.046.5 Thickness 0.08 mil 0.24 mil 0.35 mil 0.24 mil 0.79 mil Thickness 2μ6μ 9μ 6μ 20μ

The tray liner film had a maximum thickness of 1.69 mils (43 microns)and was known as PLB274Z, obtained from Multiflex Folien GmbH & Co.

The support sheet was a polypropylene sheet having a maximum thicknessof from 20 to 25 mils. The polypropylene support sheet was purchasedfrom Mullenix.

Table 35, below, summarizes the composition of various layers of FilmNos. 1-31, and provides the results of the implosion resistance test, inmillimeters of hole diameter, using the above test procedure.

TABLE 35 Implosion Results for Film Nos 1-31 As Function of CompositionWt % Avg et/α- Wt % Et/α-o + Density Implosion olefin COC COC et/α-Resistance Other Notable Components in Film (total wt (total wt (totalolefin Test Seal and Bulk Layer of No top web) top web) wt %) (g/cm³)(mm, avg) Top Web (% is wt %) 1 7.9 0 7.9 0.901 12.6 66.6% EVA 2 7.9 07.9 0.901 13.1 66.6% EVA 3 74.5 0 74.5 0.900 13.5 4 74.5 0 74.5 0.90015.0 5 74.5 0 74.5 0.887 14.4 6 74.5 0 74.5 0.905 15.9 7 7.9 0 7.9 0.90111.4 66.6% ionomer resin 8 7.9 0 7.9 0.901 0 46.6% PEC; 20% SBS1 9 32.80 32.8 0.904 0 14.9% PEC; 6.4% SBS1 10 7.9 0 7.9 0.901 0 46.6% PEC; 20%SBS2 11 7.9 0 7.9 0.901 0 66.6% SBS 3 12 74.5 0 74.5 0.870 10.2 66.6%olefin block copolymer 13 74.5 0 74.5 0.887 13.4 14 74.5 0 74.5 0.88713.3 15 61.3 0 61.3 0.887 12.5 13.4% PA 6/66 16 7.9 0 7.9 0.901 0 60%EVA2 17 74.5 0 74.5 0.905 13.5 18 72.4 2.1 74.5 0.905 16.3 19 71.2 3.374.5 0.905 16.2 20 55.8 18.7 74.5 0.905 11.6 21 45.8 28.7 74.5 0.90515.4 100% of ENB was ENB2 22 31.1 43.4 74.5 0.904 13.7 100% of ENB wasENB2 23 31.1 43.4 74.5 0.904 8.8 92% of ENB was ENB1 24 45.8 28.7 74.50.904 11 92% of ENB was ENB1 25 55.8 18.7 74.5 0.905 13.3 89% of ENB wasENB1 26 72.4 2.1 74.5 0.905 14.9 100% of ENB was ENB2 27 71.2 3.3 74.50.905 15.7 28 74.5 0 74.5 0.905 13.4 29 74.5 0 74.5 0.911 14.1Heterogeneous et/α-olefin 30 74.5 0 74.5 0.911 13.2 Homogeneouset/α-olefin 31 74.5 0 74.5 0.908 13.6 32 72.4 2.1 74.5 0.906 not tested

In Table 35, above, the amount of ethylene/α-olefin copolymer iscalculated based on ethylene/α-olefin copolymer in the seal layer andthe bulk layers, but does not include the small qualities ofethylene/alpha-olefin copolymer in the slip agents used in the outerlayers of the top web film. Although the small quantities ofethylene/α-olefin in SLIP1 and SLIP3 may have contributed to implosionresistance and slightly elevate the weight percent ethylene/alpha-olefincopolymer reported for the films, all of the films contained about thesame amounts of these slip agents so the small effect did not alter therelative implosion resistance results for the films, i.e., the implosionresistance relative to each other.

As is apparent from the data above, the top webs containing astyrene-butadiene-styrene block copolymer (Film No. 11) or a blend ofpropylene/ethylene copolymer (PEC) and styrene butadiene styrenecopolymer (Film Nos. 8-10) also exhibited poor results in the ImplosionResistance Test (average of 0 mm). The three top webs containingethylene/vinyl acetate copolymer (Film Nos. 1, 2, and 16) exhibitedmediocre implosion resistance in a room temperature Implosion ResistanceTest (average of 8.6 mm). Similarly, the only top web containing ionomerresin (Film No. 7) also exhibited mediocre poor implosion resistance inthe room temperature Implosion Resistance Test (11.4 mm).

In contrast, top web Film Nos. 21-29, which containing a blend ofethylene/alpha-olefin copolymer and cyclic olefin copolymer (i.e., COC,which was solely ethylene norbornene copolymer, ENB) exhibited goodimplosion resistance in the Implosion Resistance Test, i.e., an averageImplosion Resistance of (average value 13.7 mm). Those withpredominantly ENB1 (i.e., Film Nos. 23, 24, 25, 27, avg implosionresistance 12.2 mm), which had a density of 1.02 and a melt index of2.04 dg/min, did not perform as well as those with predominantly ENB2(Film Nos. 18, 19, 20, 21, 22, 26, average implosion resistance 14.7mm), which had a density of 0.974 and a melt index of 1.0 dg/min.

Moreover, Film Nos. 18 and 19, which contained 25 wt % to 40 wt % COC inthe seal layer in a blend with ethylene/α-olefin copolymer, exhibitedsome of the highest average implosion resistance values (16.3 mm and16.2 mm, respectively).

The top webs containing ethylene/α-olefin copolymer without cyclicolefin copolymer (i.e., Film Nos. 3-6, 12, 13, 14, 15, 17-20, 31)exhibited an average implosion resistance value of 13.8 mm in theImplosion Resistance Test conducted at room temperature.

The best implosion resistance was obtained from the top webs containinga relatively high fraction of relatively low density heterogeneousethylene/α-olefin copolymer in the seal and bulk layers, either with orwithout a COC present in the seal layer or bulk layer, so that eitherthe ethylene/α-olefin copolymer alone or the ethylene/α-olefin plus theCOC together made up at the majority of the weight of the top web film,i.e., Film Nos. 5, 6, 17, 18, 19, 21, 22, 25, 26, 27, 28, 29, and 31.These top web films exhibited an average room temperature ImplosionResistance Test Result of 14.5 mm. The films containing a low densityheterogeneous ethylene/α-olefin copolymer (0.9025 g/cm³) in the bulklayer and from 25 wt % to 40 wt % COC in the seal layer.

Although the present invention has been described in connection with thepreferred embodiments, it is to be understood that modifications andvariations may be utilized without departing from the principles andscope of the invention, as those skilled in the art will readilyunderstand. Accordingly, such modifications may be practiced within thescope of the following claims.

What is claimed is:
 1. A packaged product comprising a product and avacuum skin package surrounding the product, the vacuum skin packagecomprising (A) a support member having an upper surface; and (B) animplosion-resistant thermoplastic top web conforming with both: (i) anupper surface of the product, and (ii) a portion of the upper surface ofthe support member, the portion being uncovered by the product; andwherein the thermoplastic top web comprises a member selected from thegroup consisting of: (iii) at least one ethylene/-olefin copolymer in atotal amount of from 55 wt % to 85 wt %, based on total weight of thetop web, and (iv) a blend of ethylene/α-olefin copolymer and cyclicolefin copolymer, the ethylene/α-olefin being present in the top web ina total amount of from 30 wt % to 80 wt %, and the cyclic olefincopolymer being present in the top web in a total amount of from about 1wt % to 50 wt %, based on total weight of the top web, wherein thesupport member comprises a support sheet having a liner film laminatedthereto, the support sheet is made from a material chosen frompolypropylene and polyethylene terephthalate, wherein the liner filmcomprises a multilayer film having: (a) a bonding layer comprising atleast one member chosen from anhydride grafted polypropylene,ethylene/propylene copolymer, homogeneous ethylene/alpha-olefincopolymer having a density of 0.88 to 0.91 g/cm³, and blends thereof,the bonding layer being adhered to the support sheet, (b) an outer heatseal & food-contact layer comprising at least one member chosen frompolyolefin, ethylene methacrylic acid copolymer, ethylene methylacrylate copolymer, and ionomer resin, (c) an oxygen barrier layercomprising at least one member chosen from saponified ethylene/vinylacetate copolymer, polyvinylidene chloride, and polyamide, the oxygenbarrier layer being between the heat seal & food-contact layer and thebonding layer; (d) a first tie layer comprising an anhydride modifiedethylene/α-olefin copolymer, and (e) a second tie layer which is betweenthe first tie layer and the heat seal & food-contact layer, the secondtie layer comprising ethylene/methyl acrylate copolymer, and the linerfilm has a maximum thickness of from 1.2 mils to 2 mils.
 2. The packagedproduct according to claim 1, wherein the top web is a multilayerstructure comprising: (a) an outer heat seal and product-contact layercomprising at least one member selected from the group consisting ofethylene/α-olefin copolymer, cyclic olefin copolymer, low densitypolyethylene, high density polyethylene, ethylene/vinyl acetatecopolymer with a vinyl acetate content in the 3% to 9% range by weight,ionomer resin, ethylene methacrylic acid copolymer, and ethylene methylacrylate copolymer, (b) an oxygen barrier layer comprising a memberselected from the group consisting of saponified ethylene/vinyl acetatecopolymer, polyvinylidene chloride, and polyamide (c) a first tie layerbetween the oxygen barrier layer and the heat seal and product-contactlayer, and (d) a second tie layer between the oxygen barrier layer andan outer abuse layer, wherein each of the first and second tie layerscomprises at least one member selected from the group consisting ofethylene/carboxylic acid copolymer, ethylene/ester copolymer,anhydride-modified ethylene/alpha-olefin copolymer, anhydride-modifiedhigh density polyethylene, and anhydride modified low densitypolyethylene, wherein the first tie layer and the second tie layer aredirectly adhered to opposite surfaces of the oxygen barrier layer. 3.The packaged product according to claim 2, wherein the oxygen barrierlayer of the top web being between the heat seal and product-contactlayer and the outer abuse layer, with the outer abuse layer comprisingat least one member selected from the group consisting of low densitypolyethylene, high density polyethylene, polypropylene, polyester, andcyclic olefin copolymer.
 4. The packaged product according to claim 3,wherein the top web further comprises a first bulk layer between thefirst tie layer and the heat seal and product-contact layer, and asecond bulk layer between the second tie layer and the outer abuselayer, wherein each of the bulk layers comprises at least one memberselected from the group consisting of ethylene/alpha-olefin copolymer,cyclic olefin copolymer, ethylene homopolymer, ethylene/unsaturatedester copolymer, ionomer resin, propylene/ethylene copolymer,polystyrene, polyamide polyester, and polycarbonate.
 5. The packagedproduct according to claim 4, wherein the cyclic olefin copolymercomprises ethylene/norbornene copolymer.
 6. The packaged productaccording to claim 2, wherein the outer heat seal and product-contactlayer comprises a blend of ethylene/α-olefin copolymer and cyclic olefincopolymer having an average density of from 0.88 g/cm³ to 0.915 g/cm3.7. The packaged product according to claim 2, wherein the top web has aseal layer comprising from 10 wt % to 50 wt % cyclic olefin copolymer ina blend with from 40 wt % to 90 wt % ethylene/α-olefin copolymer.
 8. Thepackaged product according to claim 2, wherein the top web has beenirradiated by at least one member selected from the group consisting ofcorona discharge, plasma, flame, ultraviolet, X-ray, gamma ray, betaray, and high energy electron treatment, to produce a cross-linkedpolymer network.
 9. The packaged product according to claim 2, whereinthe top web exhibits an average implosion resistance of at least 11.5millimeters.
 10. The packaged product according to claim 2, wherein thetop web has a maximum thickness of from 3 mils to 9 mils.
 11. Thepackaged product according to claim 1, wherein the support member isflat and comprises a flat support sheet and a flat liner film.
 12. Thepackaged product according to claim 1, wherein the support member is atray having a bottom product support portion and side walls extendingupwardly from the product support portion, with the tray comprising alaminate comprising a support member having a liner film bonded thereto,the laminate having been thermoformed to form the tray.
 13. The packagedproduct according to claim 1, wherein the top web comprises anethylene/α-olefin copolymer having a melt index of from 0.5 to 4 dg/min.14. A vacuum skin package having an implosion-resistant top webcomprising a member selected from the group consisting of: (A) at leastone ethylene/α-olefin copolymer in a total amount of from 55 wt % to 85wt %, based on total weight of the top web, and (B) a blend ofethylene/α-olefin copolymer and cyclic olefin copolymer, theethylene/α-olefin being present in the top web in a total amount of from30 wt % to 80 wt %, and the cyclic olefin copolymer being present in thetop web in a total amount of from about 1 wt % to 50 wt %, based ontotal weight of the top web the top web being a multilayer structurecomprising: (a) an outer heat seal and product-contact layer comprisingat least one member selected from the group consisting ofethylene/α-olefin copolymer, cyclic olefin copolymer, low densitypolyethylene, high density polyethylene, ethylene/vinyl acetatecopolymer with a vinyl acetate content in the 3% to 9% range by weight,ionomer resin, ethylene methacrylic acid copolymer, and ethylene methylacrylate copolymer, (b) an oxygen barrier layer comprising a memberselected from the group consisting of saponified ethylene/vinyl acetatecopolymer, polyvinylidene chloride, and polyamide (c) a first tie layerbetween the oxygen barrier layer and the heat seal and product-contactlayer, and (d) a second tie layer between the oxygen barrier layer andan outer abuse layer, wherein each of the first and second tie layerscomprises at least one member selected from the group consisting ofethylene/carboxylic acid copolymer, ethylene/ester copolymer,anhydride-modified ethylene/alpha-olefin copolymer, anhydride-modifiedhigh density polyethylene, and anhydride modified low densitypolyethylene, wherein the first tie layer and the second tie layer aredirectly adhered to opposite surfaces of the oxygen barrier layerwherein the vacuum skin package comprises a support member comprising asupport sheet having a liner film laminated thereto, the support sheetis made from a material chosen from polypropylene and polyethyleneterephthalate, wherein the liner film comprises a multilayer filmhaving: (a) a bonding layer comprising at least one member chosen fromanhydride grafted polypropylene, ethylene/propylene copolymer,homogeneous ethylene/alpha-olefin copolymer having a density of 0.88 to0.91 g/cm³, and blends thereof, the bonding layer being adhered to thesupport sheet, (b) an outer heat seal & food-contact layer comprising atleast one member chosen from polyolefin, ethylene methacrylic acidcopolymer, ethylene methyl acrylate copolymer, and ionomer resin, (c) anoxygen barrier layer comprising at least one member chosen fromsaponified ethylene/vinyl acetate copolymer, polyvinylidene chloride,and polyamide, the oxygen barrier layer being between the heat seal &food-contact layer and the bonding layer; (d) a first tie layercomprising an anhydride modified ethylene/α-olefin copolymer, and (e) asecond tie layer which is between the first tie layer and the heat seal& food-contact layer, the second tie layer comprising ethylene/methylacrylate copolymer, and the liner film has a maximum thickness of from1.2 mils to 2 mils.
 15. A vacuum skin package having animplosion-resistant top web, the implosion resistant top web including amultilayer film comprising: (A) a heat seal and product contact layercomprising at least one ethylene/α-olefin copolymer in a total amount offrom 40 wt % to 95 wt %, based on weight of the heat seal and productcontact layer, and a cyclic olefin copolymer in an amount of from 1 wt %to 50 wt %, based on weight of the heat seal and product contact layer;(B) a heat resistant outside layer comprising at least one memberselected from the group consisting of low density polyethylene, highdensity polyethylene, polypropylene, polyester and cyclic olefincopolymer; (C) an oxygen barrier layer comprising at least one memberselected from the group consisting of saponified ethylene/vinyl acetatecopolymer, polyvinylidene chloride, and polyamide; (D) a first tie layerdirectly adhered to a first surface of the oxygen barrier layer, thefirst tie layer comprising at least one member selected from the groupconsisting of ethylene/carboxylic acid copolymer, ethylene/estercopolymer, anhydride-modified ethylene/alpha-olefin copolymer,anhydride-modified high density polyethylene, and anhydride modified lowdensity polyethylene, the first tie layer being between the oxygenbarrier layer and the heat seal and product-contact layer; (E) a secondtie layer directly adhered to a second surface, which is opposite saidfirst surface, of the oxygen barrier layer, the second tie layercomprising at least one member selected from the group consisting ofethylene/carboxylic acid copolymer, ethylene/ester copolymer,anhydride-modified ethylene/alpha-olefin copolymer, anhydride-modifiedhigh density polyethylene, and anhydride modified low densitypolyethylene, the second tie layer being between the oxygen barrierlayer and the heat resistant outside layer; (F) a first bulk layercomprising at least one member selected from the group consisting ofethylene/alpha-olefin copolymer, cyclic olefin copolymer, olefinhomopolymer, ethylene/unsaturated ester copolymer, ionomer resin,propylene/ethylene copolymer, polystyrene, polyamide polyester, andpolycarbonate, the first bulk layer being between the first tie layerand the heat seal and product-contact layer, (G) a second bulk layercomprising at least one member selected from the group consisting ofethylene/alpha-olefin copolymer, cyclic olefin copolymer, olefinhomopolymer, ethylene/unsaturated ester copolymer, ionomer resin,propylene/ethylene copolymer, polystyrene, polyamide, polyester, andpolycarbonate, the second bulk layer between the second tie layer and anouter abuse layer wherein the vacuum skin package comprises a supportmember comprising a support sheet having a liner film laminated thereto,the support sheet is made from a material chosen from polypropylene andpolyethylene terephthalate, wherein the liner film comprises amultilayer film having: (a) a bonding layer comprising at least onemember chosen from anhydride grafted polypropylene, ethylene/propylenecopolymer, homogeneous ethylene/alpha-olefin copolymer having a densityof 0.88 to 0.91 g/cm³, and blends thereof, the bonding layer beingadhered to the support sheet, (b) an outer heat seal & food-contactlayer comprising at least one member chosen from polyolefin, ethylenemethacrylic acid copolymer, ethylene methyl acrylate copolymer, andionomer resin, (c) an oxygen barrier layer comprising at least onemember chosen from saponified ethylene/vinyl acetate copolymer,polyvinylidene chloride, and polyamide, the oxygen barrier layer beingbetween the heat seal & food-contact layer and the bonding layer; (d) afirst tie layer comprising an anhydride modified ethylene/α-olefincopolymer, and (e) a second tie layer which is between the first tielayer and the heat seal & food-contact layer, the second tie layercomprising ethylene/methyl acrylate copolymer, and the liner film has amaximum thickness of from 1.2 mils to 2 mils.